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Late Finishers and Early Starters Bird Populations 8:168-170 Reprinted with permission BTO News 246:6-7 © British Trust for Ornithology 2003 LATE FINISHERS AND EARLY STARTERS DAVID GLUE British Trust for Ornithology The National Centre for Ornithology The Nunnery, Thetford Norfolk, IP24 2PU, United Kingdom BTO Research Biologist, David Glue, describes how a mild autumn and winter, led to late and early nesting activity among UK birds. TARDONES Y TEMPRANEROS El biólogo investigador del BTO David Glue describe cómo un otoño e invierno suaves han dado lugar a actividad de nidificación tardía y temprana en aves del Reino Unido. BTO volunteers charted a more productive though there were some surprises. The BTO breeding season for most resident and migrant Barn Owl Monitoring Programme showed that, species in 2002 compared with 2001. The early after a flying start in spring 2002, pairs were signs for 2003 are very hopeful. egg-laying a fortnight earlier than normal. About 10% of the monitored birds produced late clutches, with successes in November INDIAN SUMMER HELPS LATE (Lincs, Sussex and Notts) and even December NESTERS 2002, defying unfavourable hunting conditions. A pleasantly changeable midsummer mix of One unrivalled pair raised broods of four and weather in 2002 prolonged the breeding season nine young near Peterborough (Cambs). for many. Observations from nestbox Breeding activity was checked in mid monitoring revealed the latest ever free-flying December, as arctic air brought sharp frosts on broods of Little Owl, Great Tit and Pied 18–19th. Then over the Christmas week, Flycatcher, a result of repeat layings. The warm, unseasonably warm air lifted temperatures to a dry Indian summer heat in September saw balmy 15°C in sheltered South Devon and successful late breeding by a number of species. North Wales, prompting a scatter of nesting Arguably, ‘Nestbox of the Year’ was at Treswell attempts into the New Year. Early breeding Wood (Notts), which successfully disgorged its activity involved Golden Eagle, Raven, Ring- final brood, Tawny Owl spring twins, which necked Parakeet, Nuthatch and tits. Nesting were followed by one, two and two young Stock was invariably in the shelter of suburbia and Dove respectively (pers. comm. Chris du Feu). rural hamlets, with egg-laying and active young of Mallard (Herts, Central London), Robin (York, Leicester) and Blackbird (Sout- BLACKBIRD AND ROBIN EXPLOIT hampton, Surrey, Pembroke) being reported NEW YEAR WARM SPELLS from parks, shopping malls, allotments and Nesting activity continued low key during a hospital grounds. mild, if very wet December. Most reports A raw northerly chill from 3–11 January 2003, involved Woodpigeon and Feral Pigeon, when frosts dipped to –18°C at Aviemore [168] LATE FINISHERS AND EARLY STARTERS (Highland), destroyed most early nesting Bitterns in modern times apparently led to only attempts. However, record high monthly tem- a few extra booming males. peratures in the third week, with temperatures topping 18°C at Aboyne (Grampian), prompted the first Tawny Owl clutches and broods, from MARCH HEAT HELPS RESIDENTS Cheshire, Gwent, Nottingham and Aberdeen AND SPRING MIGRANTS (see Box). This activity was fuelled by plentiful March roared in on a mild southwesterly Field Voles and Wood Mice, which were in part airflow, prompting a spate of egg-laying as some a product of a bumper beech mast crop. resident species, including Grey Heron, Robin, thrushes and Rook played ‘catch-up’ in the first week. Some noteworthy cases were Cormorant VALENTINE’S DAY CHILL (Isles of Scilly), Dipper (Gwent) and Lapwing FRUSTRATES RESIDENTS AND (Bucks). Migrants, including Stone Curlew WINTER VISITORS (Breckland, 3rd), Sandwich Tern (Anglesey, 16th) Frustratingly, temperatures see-sawed violently and Ring Ouzel (Durham 17th), were quickly during February, although overall it was drier noted back at traditional breeding sites by and sunnier than normal. Early blizzards and contributors to BTO/BirdWatch Ireland widespread snowfall extended southwards into Migration Watch. London suburbs, followed by a destructive raw Record wintering numbers of Avocet and easterly chill around St Valentine’s Day. Mediterranean Gulls in certain counties have led The recovery of 14 dead Wrens, crammed into to welcome extra breeding pairs. Peregrines, a single roosting ‘pouch’ near Church Stretton happily nesting atop Battersea Power Station (Shrops) was a chilling find. Similarly, emaciated since 2001, were joined by further pairs and oiled corpses, and ailing birds, including prospecting in London. The UK Peregrine Little Auk, Puffin, Snipe, Water Rail, Goldcrest Survey 2002 had showed an increasing use of and Waxwing, were reported from the man-made structures, notably ecclesiastical BTO/WWT/RSPB/JNCC Wetland Bird Survey, buildings, bridges, chimneys, warehouses, or were passed to the BTO’s Ringing Unit or pylons and, most intriguingly, trees. In a similar Natural History Museum (Tring). Fortunately, fashion, Raven, having claimed Chester the wintry episodes were short-lived and the Cathedral, showed interest in further ‘artificial’ absence of lengthy lying snow and penetrating structures as nest sites, along with trees and frosts helped the survival prospects of unusual quarries, enhancing prospects of their range over-wintering Ring Ouzel (Derbys), Whinchat extension yet farther eastwards in 2003. (Bucks), Dusky Warbler (Suffolk), Yellow- With high pressure anchored over the UK browed Warbler, Little Stint, Whimbrel and midmonth, temperatures climbed to 19°C at Spoonbill (various sites). High numbers of voles Aberystwyth (Dyfed) by St Patrick’s Day. Warm, will have supported larger than usual numbers glorious sunshine, leaf bud burst, and increased of Short-eared Owls, Long-eared Owls and aerial insect food supplies led to a surge in egg- Great Grey Shrikes. laying of many species, including grebes, By the end of the month, 13 nesting species dabbling duck, rails, some plovers and corvids, had been reported (five fewer than this stage in alongside Woodcock (Wilts), Long-eared Owl 2002). This included egglaying by Egyptian (Derbys) and Woodlark (Surrey) in the third Goose (Southeast), Moorhen (Gloucs), Starling week. (Co Cork) and Mistle Thrush (Hereford). The As in 2002, we look set for a possibly produc- largest UK winter influx and dispersal of tive breeding season. [169] DAVID GLUE EARLY EGG-LAYING TAWNY OWLS When long-time BTO Nest Recorders, Bryan Perkins and Colin Lythgoe, undertook the annual spring-clean of their nestboxes in Quakers Coppice, Crewe (Cheshire) on 27 February, they were surprised to be confronted by a large fledgling Tawny Owl and remains of two other chicks (fratricide is regular in this species). By 3 March the fledged owlet was found happily roosting alongside two older siblings and an adult in woodland nearby. Back-calculation, based upon observations made, suggested that a clutch of five eggs, laid during the unseasonably mild spell between Christmas 2002 and the New Year, produced five hatchlings, three surviving to leave the nestbox. Meanwhile, Julie Stevens of Retford (Notts) had chanced across a large, dazed juvenile Tawny Owl road casualty. A nearby nestbox was found to be holding another three young. Local owl expert, Derick Scott, considered that the road casualty was fit for release and was the result of an egg laid around 6–9 January. Several further clutches were started before the close of January (see above). Tawny Owls adjust their breeding season around an often fickle food supply but such exceptionally early clutches are rare. The bulk of clutches are normally laid in late March, so that foraging parents can satisfy developing young in early May on an ephemeral crop of larger mammalian prey. Just occasionally, as in Winter 2002/03, a super-abundant food supply and mild weather over- rides this time-table. In Autumn 2002, a huge crop of beech mast and other woodland fruits, fuelled locally high populations of rodent prey, enabling Tawny Owls to take the advantage via early egglaying. David Glue BTO NEST RECORD SCHEME Completed Nest Record Cards for nests encountered are valued by the BTO. For a free starter pack please contact: Peter Beaven, at BTO Thetford HQ. [170].
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